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Clozapine is one of the most widely used second-generation antipsychotic drugs (SGAs) for the treatment of schizophrenia. Despite advantages over first-generation drugs, clozapine still shows significant side effects and interindividual variations in efficacy. In order to ensure frequent therapeutic drug monitoring (TDM) and improve the compliance of psychiatric patients undergoing clozapine treatment, two novel dried microsampling approaches based on whole blood and plasma volumetric absorptive microsampling (b-VAMS and p-VAMS) and microfluidic generated-dried blood spot technology (mfDBS) were developed and coupled to HPLC with electrochemical detection (ED). The proposed miniaturized strategies by means of VAMS and microfluidic channel-based devices provide several advantages in terms of collection, storage, and handling compared to classical blood and plasma processing. Satisfactory validation results were obtained for all microsampling platforms, with mean extraction yields >85.1%, precision as relative standard deviation (RSD) < 5.1%, and stability < 4.5% analyte loss after 30 days for p-VAMS; mean extraction yields > 83.4%, precision RSD < 5.4%, and stability < 4.6% analyte loss after 30 days for b-VAMS, and mean extraction yields > 74.0%, precision RSD < 5.6%, and stability < 4.9% analyte loss after 30 days for mfDBS. The original microsampling methodologies have been successfully applied to the blood and plasma collected from five psychiatric patients for the monitoring of the levels of clozapine and its main metabolites, providing robust and reliable quali-quantitative results. Comparisons between results of the two dried microsampling technologies with those obtained by classic fluid plasma analysis were in good agreement and have demonstrated that the proposed miniaturized approaches could be suitable for TDM purposes. [ABSTRACT FROM AUTHOR]

Clozapine is one of the most widely used second-generation antipsychotic drugs (SGAs) for the treatment of schizophrenia. Despite advantages over first-generation drugs, clozapine still shows significant side effects and interindividual variations in efficacy. In order to ensure frequent therapeutic drug monitoring (TDM) and improve the compliance of psychiatric patients undergoing clozapine treatment, two novel dried microsampling approaches based on whole blood and plasma volumetric absorptive microsampling (b-VAMS and p-VAMS) and microfluidic generated-dried blood spot technology (mfDBS) were developed and coupled to HPLC with electrochemical detection (ED). The proposed miniaturized strategies by means of VAMS and microfluidic channel-based devices provide several advantages in terms of collection, storage, and handling compared to classical blood and plasma processing. Satisfactory validation results were obtained for all microsampling platforms, with mean extraction yields >85.1%, precision as relative standard deviation (RSD) < 5.1%, and stability < 4.5% analyte loss after 30 days for p-VAMS; mean extraction yields > 83.4%, precision RSD < 5.4%, and stability < 4.6% analyte loss after 30 days for b-VAMS, and mean extraction yields > 74.0%, precision RSD < 5.6%, and stability < 4.9% analyte loss after 30 days for mfDBS. The original microsampling methodologies have been successfully applied to the blood and plasma collected from five psychiatric patients for the monitoring of the levels of clozapine and its main metabolites, providing robust and reliable quali-quantitative results. Comparisons between results of the two dried microsampling technologies with those obtained by classic fluid plasma analysis were in good agreement and have demonstrated that the proposed miniaturized approaches could be suitable for TDM purposes.

Volumetric absorptive microsampling (VAMS) is increasingly proposed as a clinically reliable therapeutic drug monitoring (TDM) sampling methodology. The study aimed to establish the reliability and real-life feasibility of patient self-collected capillary VAMS for TDM of antiseizure medication (ASMs), using plasma ASMs concentrations from venous blood as a reference standard. Nurses collected venous and capillary blood samples using VAMS. Afterward, persons with epilepsy (PWE) performed VAMS sampling by themselves. All samples were analyzed by UHPLC-MS/MS. We performed a cross-validation study, comparing ASMs concentrations obtained by VAMS nurses and patients' self-collected versus plasma through Bland-Altman analysis and Passing-Bablok regression. We enrolled 301 PWE (M: F 42.5%:57.5%; mean age 44±16 years), treated with 13 ASMs, providing a total of 464 measurements. Statistical analysis comparing VAMS self-collected versus plasma ASMs concentrations showed a bias close to zero and slope and intercept values indicating a good agreement for CBZ, LCS, LEV, LTG, OXC, PB, and PHT, while a systematic difference between the two methods was found for VPA, PMP, TPM and ZNS. This is the first study showing the reliability and feasibility of the real-world application of PWE self-collected VAMS for most of the ASMs considered, giving a promising basis for at-home VAMS applications. [Display omitted] • Real-life data on using VAMS for antiseizure medication (ASMs) are lacking. • Cross-validation investigated reliability and feasibility of VAMS vs venous blood. • VAMS showed good accuracy and reliability for CBZ, LCS, LEV, LTG, OXC, PB, and PHT. • Comparison between self and nurse-collected VAMS demonstrates good correlation. • VAMS was demonstrated as a promising tool for future TDM at-home applications. [ABSTRACT FROM AUTHOR]

Yahdiana Harahap,1 Rasmina Diptasaadya,1 Denni Joko Purwanto2 1Faculty of Pharmacy, Universitas Indonesia, Depok, West Java 16424, Indonesia; 2Functional Medical Staff of Surgical Oncology, Dharmais Cancer Hospital, Jakarta 11420, IndonesiaCorrespondence:Yahdiana HarahapFaculty of Pharmacy, Universitas Indonesia, Pondok Cina, Beji, Depok, West Java 16424, IndonesiaPhone/ Fax +62 818222192/021 78849001-003 Email yahdiana03@yahoo.comAbstract: An infectious disease, COVID-19, caused by a new type of coronavirus, has been discovered recently. This disease can cause respiratory distress, fever, and fatigue. It still has no drug and vaccine for treatment and prevention. Therefore, WHO recommends that people should stay at home to reduce disease transmission. Due to the quarantine, FDA stated that this could hamper drug development clinical trial protocols. Hence, an alternative sampling method that can be applied at home is needed. Currently, volumetric absorptive microsampling (VAMS) has become attention in its use in clinical and bioanalytical fields. This paper discusses the advantages and challenges that might be found in the use of VAMS as an alternative sampling tool in clinical trials and therapeutic drug monitoring (TDM) during the COVID-19 pandemic. VAMS allows easy sampling, can be done at home, storage and delivery at room temperature, and the volume taken is small and minimally invasive. VAMS is also able to absorb a fixed volume that can increase the accuracy and precision of analytical methods, and reduce the hematocrit effects (HCT). The use of VAMS is expected to be implemented immediately in clinical trials and TDM during this pandemic considering the benefits it has.Keywords: clinical trials, COVID-19, drug development, therapeutic drug monitoring, TDM, volumetric absorptive microsampling, VAMS

• A method for TDM of methotrexate and its metabolites was developed and validated. • An on-line SPE system has been used to simplify the extraction. • The applicability of VAMSTM technology for the ambulatory setting is demonstrated. • With LC-MS, a simple and cost-efficient detector is applied. • A correlation factor between serum and whole-blood was investigated. High-dose methotrexate is part of the polychemotherapy protocols for the treatment of Acute lymphoblastic leukaemia (ALL) with therapeutic drug monitoring (TDM) to adjust leucovorin rescue. An immunoassay is commonly used to analyse serum samples collected via venous blood sampling. However, immunoassays cannot distinguish between the parent drug and its metabolites. Besides, the blood volume required by venous blood sampling is high. Therefore, the aim of this project was to develop a fast, simple, reliable and cost-efficient micro sampling bioanalytical method using capillary blood to minimize the harm of children and to analyse both methotrexate and its metabolites. To achieve this aim, a LC-MS method with on-line solid phase extraction (SPE) for the simultaneous detection of methotrexate and its metabolites from capillary blood using volumetric-absorptive-microsampling (VAMS) technology was developed and fully validated. Besides, the method was also validated and modified for serum samples to compare the results with the immunoassay. A single-quadrupole MS detector was used for detection. Through the use of on-line SPE technology, a lower limit of quantitation of 0.03 µM for MTX and 7-OH-MTX and of 0.05 µM for DAMPA from a 10 μL capillary blood sample was achieved. The accuracy is between 90.0 and 104% and the precision between 4.7 and 12% for methotrexate and its metabolites, respectively. Because of the cross reactivity of the immunoassay a cross-validation was not successful. Besides, a correlation factor of 0.46 for MTX between plasma and whole-blood was found. A fast, simple, reliable and cost-efficient extraction and analysis LC-MS method could be developed and validated, which is applicable in ambulatory and clinical care. [ABSTRACT FROM AUTHOR]

Psychiatric disorders are usually treated with antipsychotic agents belonging to different pharmacological and chemical classes, the most recent ones collectively known as "third-generation antipsychotics", such as cariprazine, approved in 2015 for the treatment of patients affected by schizophrenia. For these patients, a frequent therapeutic drug monitoring (TDM) becomes essential to assess compliance and to optimise and personalise their therapy, also due to cariprazine interindividual variability and narrow therapeutic range. In this study, a bioanalytical method featuring miniaturised sampling and pretreatment was developed, based on volumetric absorptive microsampling (VAMS) for TDM of psychiatric patients under cariprazine treatment and compared to a reference method based on fluid plasma analysis. Minimally invasive whole blood VAMS was coupled to an original instrumental method based on ultra-high performance liquid chromatography hyphenated to mass spectrometry (UHPLC-MS). A feasible and streamlined, yet reliable VAMS pretreatment protocol was carefully optimised and the VAMS-UHPLC-MS methodology was validated with satisfactory results in terms of linearity (r 2 > 0.9970 in the 1.5–100 ng/mL range), precision (%RSD < 11.7), extraction yield (> 90.0 %) and matrix effect (8.2 ≤ %RE ≤ 10.9). Finally, the microsampling approach coupled to UHPLC-MS was successfully applied to the TDM of psychiatric patients treated with cariprazine and compared with standard fluid plasma analysis, providing reliable quali-quantitative results, and proving to be readily applicable to the clinical practice in TDM programs as a useful alternative to cariprazine plasma analysis. This is the first report of a successful microsampling application, and in particular the first report of VAMS application, for the TDM of cariprazine. [Display omitted] • Original VAMS-UHPLC-MS method development, validation and application. • First study on miniaturised whole blood sampling for cariprazine analysis • Successful application for the TDM of patients undergoing cariprazine therapy. • Results were satisfactorily compared with a classic procedure for plasma analysis. • Favorable analytical and logistic performance for TDM of patients under cariprazine. [ABSTRACT FROM AUTHOR]

Volumetric absorptive microsampling (VAMS) has emerged as a minimally invasive alternative to conventional sampling. However, the applicability of VAMS must be investigated clinically. Therefore, the feasibility of at-home sampling was investigated for the kinase inhibitors nilotinib, cabozantinib, dabrafenib, trametinib and ruxolitinib and evaluated regarding the acceptance of at-home microsampling, sample quality of at-home VAMS and incurred sample stability. In addition, clinical validation including three different approaches for serum level predictions was performed. For this purpose, VAMS and reference serum samples were collected simultaneously. Conversion of VAMS to serum concentration was based either on a linear regression model, a hematocrit-dependent formula, or using a correction factor. During the study period 591 VAMS were collected from a total of 59 patients. The percentage of patients who agreed to perform VAMS at home ranged from 50.0 % to 84.6 % depending on the compound. 93.1 % of at-home VAMS were collected correctly. Regarding the drug stability in dried capillary blood, no stability issues were detected between on-site and at-home VAMS. Linear regression showed a strong correlation between VAMS and reference serum concentrations for nilotinib, cabozantinib, dabrafenib and ruxolitinib (r 0.9427 – 0.9674) and a moderate correlation for trametinib (r 0.5811). For clinical validation, the acceptance criteria were met for all three approaches for three of the five kinase inhibitors. Predictive performance was not improved by using individual hematocrit instead of population hematocrit and was largely independent of conversion model. In conclusion, VAMS at-home has been shown to be feasible for use in routine clinical care and serum values could be predicted based on the measured VAMS concentration for nilotinib, cabozantinib, and dabrafenib. [Display omitted] • Volumetric absorptive microsampling is suitable for use in routine clinical care. • This dried matrix method can be used to monitor the exposure of kinase inhibitors. • Individual hematocrit values are not required for serum level prediction. • All three conversion methods led to comparable results. • Serum concentrations can be predicted for nilotinib, cabozantinib, and dabrafenib. [ABSTRACT FROM AUTHOR]

For therapeutic drug monitoring (TDM) of axitinib, the new volumetric absorption microsampling technology (VAMS™) was applied to obtain capillary blood samples in an ambulatory setting and the results were compared to plasma samples as the gold standard. On-line solid phase extraction (SPE) applying a Turboflow HTLC Cyclone™ 1.0 × 500 mm column was used to reduce costs and working time. For the analytical separation, a Kinetex 2.6 µm C18 100 Å, 100 × 3.0 mm column with a flow rate of 0.3 mL/min in gradient mode was utilised. The mobile phase consisted of acetonitrile, water and formic acid (A: 05:95:0.1 v/v and B: 95:05:0.1 v/v). For the detection, a single-quadrupole MS detector was used. Through the use of on-line SPE technology, it is possible to reach a LLOQ of 0.5 µg/L from a 10 µL capillary blood sample. For lower concentrations, a MS/MS-detector coupled with the same chromatographic system was applied reaching a LLOQ of 0.04 µg/L. This newly developed method was validated with both detectors at different calibration ranges for plasma and capillary blood as matrix. The precision of the within- and between-runs was within a range of 0.6–7.8% and 1.8 – 14% CV, respectively, while the accuracy was within a range of 81.2–115% and 87.7–116%, respectively. A reliable, simple, less personnel-intensive and cost-efficient extraction and analysis LC-MS and LC-MS/MS method could be developed and validated, which is applicable in ambulatory and clinical care. [Display omitted] • A versatile method for TDM of axitinib was developed and validated. • An on-line SPE system has been used to simplify the extraction. • The applicability of VAMS™ technology for the ambulatory setting is demonstrated. • With LC-MS, a simple and cost-efficient detector is applied. [ABSTRACT FROM AUTHOR]

• The VAMS method is capable for quantification of ten kinase inhibitors. • A compound specific VAMS-to-plasma conversion factor was established. • Clinical feasibility was demonstrated for patient samples under real-life setting. • Trametinib VAMS-to-plasma distribution was concentration-dependent. Personalized dosing of kinase inhibitors (KI) might be beneficial in oral anti-cancer therapy to overcome individual pharmacokinetic variability. Volumetric absorptive microsampling (VAMS) has emerged as an attractive alternative compared to conventional invasive sampling methods enabling remote and frequent specimen collection. Therefore, an LC-MS/MS VAMS method was developed and validated to monitor drug exposure of ten KI from 20 µL dried capillary blood. The assay includes the KI cabozantinib, dabrafenib, nilotinib, and osimertinib with a calibration range of 6–1500 ng/mL and afatinib, axitinib, bosutinib, lenvatinib, ruxolitinib and trametinib within a range of 2–500 ng/mL. Using acetonitrile containing isotope labelled internal standards (IS) as solid-liquid extraction solvent, analytes and IS were detected by multiple reaction monitoring (MRM) after electro-spray ionization (ESI) in positive ionization mode after chromatographic separation using a phenyl-hexyl column. The method was validated according to the FDA and EMA guidelines for bioanalytical method validation and in accordance with the guideline of the International Association for Therapeutic Drug Monitoring and Clinical Toxicology for dried blood spot-based methods. The calibration model was linear and reproducible for all KI (R2> 0.994). Furthermore, the validation demonstrated that the VAMS method is accurate, precise, and sensitive. The method fulfilled the acceptance criteria for matrix effects, recovery, carry over, selectivity as well as for the haematocrit effect and all substances proved to be stable in dried condition for at least six weeks at room temperature. In vitro experiments using spiked venous blood were conducted to establish a VAMS-to-plasma conversion factor for each analyte for comparison of VAMS and plasma concentrations. The method was successfully used in a real-life setting demonstrating its applicability in clinical routine. VAMS concentrations of afatinib, cabozantinib, dabrafenib, nilotinib, ruxolitinib and trametinib were assessed in capillary blood samples collected from either trained healthcare professionals or patients at home. [ABSTRACT FROM AUTHOR]

• New-generation antidepressant agents cannot be effective in the same way on all patients. • Therapeutic drug monitoring (TDM) can help personalise therapy. • Microsampling is useful for simplifying monitoring procedures. • Volumetric absorptive microsampling (VAMS) is a recent, advanced technique. • Reliable analytical results have been obtained on both blood and oral fluid microsamples. Patients suffering from major depression and related pathologies (feeding and eating disorders, obsessive-compulsive disorder, post-traumatic stress disorder, anxiety disorders, etc.) are usually treated with antidepressant agents belonging to several pharmacological and chemical classes; the most recent of these agents are collectively known as "new-generation antidepressants". In these patients, therapeutic drug monitoring (TDM) with the determination of drug and metabolite blood levels is one of the most useful procedures to optimise and personalise the treatment, enhancing both effectiveness and safety. A new approach is proposed in this study, based on microsampling of both blood and oral fluid by means of volumetric absorptive microsampling (VAMS). This approach makes sampling and storage much simpler and even self- and at-home-sampling possible, while retaining reliability, vastly increasing analyte stability and reducing overall expenses. The microsamples were pretreated by means of microextraction by packed sorbent (MEPS) on C2 sorbent and analysed by liquid chromatography with sequential spectrophotometric and spectrofluorimetric detection (HPLC-UV-FL). Method validation results were satisfactory (extraction yield >84%, precision RSD < 8.9%, stability>85.0% after 3 months). Application to blood and oral fluid VAMS from patients treated with four possible different antidepressants (sertraline, fluoxetine, citalopram and vortioxetine) provided results always in good agreement with those obtained from the corresponding fluid matrices, including the levels of drug metabolites. [ABSTRACT FROM AUTHOR]